Image processing method and an image processing apparatus

Abstract

A sub-pixel disparity cost volume which contains initial cost values of dissimilarity calculated between the pixel values on a standard image of a plurality of parallax images and the interpolated sub-pixel values on the counterpart image or images other than said standard image is prepared for a plurality of parallax images of objects in a three-dimensional structure composed of horizontal, vertical and disparity axes. Noise signals on the calculated cost values in the sub-pixel disparity cost volume are eliminated by using an edge-preserving filter which allocates bigger weights between two cost values whose pixel coordinates have similar pixel values on the standard image, for preserving edges or boundaries of the objects. A sub-pixel disparity is selected, which gives the minimum cost value in the specific disparity range around a previously-given initial pixel-wise or sub-pixel disparity at each pixel coordinate on the standard image. Thus the distance to the objects is estimated from the computed disparity. Precise disparity can be computed by preparing a sub-pixel disparity cost volume and then computing the sub-pixel resolution disparity. Further, the necessary processing time can be reduced by parallel computation manner.

What is claimed is: 
     
         1 . An image processing method for estimating the distance to objects from a plurality of parallax images, comprising:
 preparing a sub-pixel disparity cost volume which contains initial cost values of dissimilarity calculated between the pixel values on a standard image of said plurality of parallax images and the interpolated sub-pixel values on the counterpart image or images other than said standard image in a three-dimensional structure composed of horizontal, vertical and disparity axes,   eliminating noise signals on said initial cost values in the sub-pixel disparity cost volume while preserving edges or boundaries of the objects by using an edge-preserving filter which allocates bigger weights between two cost values whose pixel coordinates have similar pixel values on the standard image, and   selecting a sub-pixel disparity which gives the minimum cost value in the specific disparity range around a previously-given initial pixel-wise or sub-pixel disparity at each pixel coordinate on the standard image to estimate the distance to the objects from the computed disparity.   
     
     
         2 . The image processing method for estimating the distance to objects from a plurality of parallax images according to  claim 1 ,
 wherein said plurality of parallax images are those captured by image capturing means.   
     
     
         3 . An image processing apparatus for estimating the distance to objects from a plurality of parallax images, comprising:
 a cost volume preparing portion for preparing a sub-pixel disparity cost volume which contains initial cost values of dissimilarity calculated between the pixel values on a standard image of said plurality of parallax images and the interpolated sub-pixel values on the counterpart image or images other than said standard image in a three-dimensional structure composed of horizontal, vertical and disparity axes,   a filtering portion for eliminating noise signals on the initial cost values in the sub-pixel disparity cost volume while preserving edges or boundaries of objects by using an edge-preserving filter which allocates bigger weights between two cost values whose pixel coordinates have similar pixel values on the standard image,   a disparity selecting portion for selecting a sub-pixel disparity which gives the minimum cost value in the specific disparity range around a previously-given initial pixel-wise or sub-pixel disparity at each pixel coordinate on the standard image, and   a distance estimating portion for estimating the distance to the objects from the computed disparity.   
     
     
         4 . An image processing apparatus for estimating the distance to objects from a plurality of parallax images,
 wherein said device further comprises a plurality of image capturing means for capturing a plurality of parallax images of the objects,   said plurality of parallax images are captured by said image capturing means.